The present invention relates generally to new and useful devices and methods of packaging food products, and more specifically, to improved adjustable food casing sizing devices and methods of stuffing food products in tubular casings.
In the manufacture of sausage products, a tubular food casing, such as nonedible cellulose is loaded onto a stuffing horn of a filling machine and stuffed with an emulsion, usually comprised of comminuted meat together with fillers, seasonings, spices, etc. In the case of small sausage products, like frankfurters the filled casings are twisted, tied or clipped into suitable links at predetermined intervals and further processed. For larger sausage products, like bolognas, salamis, and the like the meat emulsion is introduced into larger, heavier walled fibrous type casings and formed into chubs or lengthy individual sausage sticks.
In preparing large diameter sausage products, like bologna, an important consideration is the maintenance of accurate size control over the entire length of the sausage stick. It is particularly important that the diameter of the large sausage products be controlled carefully so that meat packers are able to cut the sausage into slices of predetermined thickness and diameter for prepackaging. The objective is to have a given number of slices weigh precisely a predetermined amount for each package.
In stuffing larger sausage products, however, there is some tendency for diameter variations to occur which may be due to varying stretch properties of casings and meat emulsion charging pressures. There may be less variation in product diameter with sausage stuffed in fibrous casings than nonreinforced type casings. Nevertheless, meat processors are constantly striving to improve operations that affect finished package yields. Constant control during stuffing of green stick diameter assures more uniform slice weight and minimizes package over and under weight variations.
To achieve greater dimensional uniformity in stuffing larger food casings, sizing devices have been used. Diametrical stretching of the casing is performed by longitudinally passing the tubular casing prior to filling, in most instances over a stationary type sizing device which operates to stretch the casing to the stuffed diameter recommended by the manufacturer. In addition to the stretching action of the sizing device, casing moving over some devices generates friction. This creates drag or holdback forces on the casing increasing the diameter of the filled casing and vice versa depending on the extent of the forces being exerted.
While diametrical sizing and holdback are desirable to provide fully stuffed food products of dimensional uniformity, fine adjustments either increasing or decreasing the outside diameter of a sizing device may become necessary during stuffing for optimal sizing performance. As previously indicated, variations in product diameter occur during stuffing cycles, for example, as a result of variations in stretch characteristics in a given batch of casing.
U.S. Pat. Nos. 3,457,588 and 3,553,769 provide an adjustable sizing device with a plurality of sizing elements which can be radially displaced relative to the stuffing horn by turning multiple connecting shafts. The sizing device, including connecting shafts are fixedly connected to the stuffing horn, and is designed to accommodate individual lengths of unshirred tubular casing. U.S. Pat. No. 4,202,075 also employs a means for adjusting the displacement of a sizing device which is formed from a tubular core. Adjustments in the displacement of the expanded portion of the tubular core cannot be made automatically during the stuffing cycle.
U.S. Pat. No. 4,535,508 discloses an expandable casing sizing mechanism with outwardly displacable sizing members for engaging the casing when the device is mounted onto the stuffing horn. The casing sizing device is nonadjustable. Like U.S. Pat. No. 4,535,508, U.S. Pat. No. 4,512,059 has rigid petal-like sizing members which become outwardly expanded against the inner surface of the casing. The force for moving the petals is supplied by the casing itself. U.S. Pat. No. 4,528,719 comprises a two-piece sizing ring. Expansion of the casing sizing engaging elements is achieved by compressing one element inside the other.
U.S. Pat. Nos. 4,077,090 and 4,164,057 disclose a combination sizing disc and snubbing ring assembly. The sizing disc is mounted on a slidable sleeve on the stuffing horn and moves reciprocally, engaging the snubbing ring to form a braking surface for regulating the frictional forces developed to effect braking action and casing holdback. As in the case of most of the foregoing sizing ring assemblies, the disclosures of U.S. Pat. Nos. 4,077,090 and 4,164,057 do not suggest means for adjusting ring diameter during stuffing operations. Accordingly, there is a need for an improved food casing sizing device which will offer greater flexibility in making spontaneous adjustments for "fine tuning" ring diameter and diametrical tension being applied to casings during stuffing operations.